To vaccinate or not to vaccinate? The current meningoccocol meningitis and whooping cough epidemics have prompted o practice nurse and vaccinator to ponder the arguments against vaccination and the dilemmas these pose for health professionals.

The diseases for which New Zealand children are immunised were disappearing before the vaccines were used, according to anti-immunisation supporters. That was a sentiment put to me last year at a course for vaccinators. It is significant for a number of reasons. Firstly, as a practice nurse and independent vaccinator, I believe in the right to choose or refuse treatment. But I am unclear about accountability when considering the consequences of decisions made about children's rights to health. Secondly, at times I am at a toss as to what to say to mothers when they choose not to vaccinate their children or delay or partly vaccinate their children. This paper is my reply to that dilemma, heightened by the current meningococcal and pertussis epidemics.

Speaking at the New Zealand 2003 Immunisation Conference last year, senior lecturer in immunology and microbiology at Otago University, Glen Buchan, said the vaccination debate had been caught up in a growing social problem--the problem of scientific ignorance. He suggested that what people don't understand, they fear. (1)

On one side of the debate, we have health professionals and scientists who are trained in the practice of scientific method. This has disadvantages, as it makes them cautious about making claims outside the bounds of what they know to be true. On the other side, is a smart but vocal group of those opposed to immunisation. These groups appear to be irreconcilable. In the middle is the quiet majority who try and gather information as best they can. Unfortunately, such information is written by health professionals in complex and difficult academic language, white the vocabulary of the anti-lobby is dramatic, widely reported and difficult to counteract.

The anti-immunisation movement is becoming more organised with time and the lessening of the public's exposure to the effects of vaccine-preventable diseases has provided an environment suitable for this movement to have a profound influence on parents.

Low immunisation rates have been explained primarily in terms of access problems, parental apathy, and provider misconceptions about contraindications. (2) A research study has identified the eight predominant rationales people have for refusing to have their children vaccinated: vaccines are dangerous; vaccines play a causal rote in the development of various diseases and conditions; vaccines are ineffective; homeopathy is an alternative to vaccination; the pertussis vaccine causes brain damage; the diseases vaccines are meant to prevent have declined owing to better sewerage, water, hygiene and nutrition; vaccines erode the immune system; and good diet, exercise, clean water and fresh air will develop natural immunity, making vaccination unnecessary. (2)

Of particular interest highlighted by the study is the claim that the diseases vaccines are meant to prevent have declined, due to better sewerage, water, hygiene and nutrition and not due to vaccination. While it is not the most common claim for withholding vaccination (it is the sixth commonest rationale), it is one I would like to focus on, as I hear it often. It is an example of a decision made as a result of poor knowledge and founded on misleading information and statistics.

The Immunisation Advisory Centre (IMAC), based at the University of Auckland, has researched the claim that "vaccination has not been responsible for the major decline in infectious diseases", propounded by the Immunisation Awareness Society (IAS). (3- Based on unsound interpretation of data, (4) the IAS says "it has been estimated that only 3.5 percent of the decline in death rate from infectious diseases and drugs can be attributed to the combined effect of vaccination and drugs." (5)

The data quoted is misleading, as it is displayed in graphs spanning 70 years (from 1900 to 1970). For example, this means that the graphs are unable to show the natural disease cycles, the responses of vaccine introduction, and effects of campaigns after 1970.

The IMAC responded with a critique of the IAS's pamphlet What's all the fuss about? White highlighting the inadequacies of the data used, the IMAC reinforced the fact that better living conditions, including safe water and antibiotics, had, indeed, reduced infectious disease transmission, but not to the point of eradication. There have been many scientific studies carded out, with copious amounts of literature to support the rote of vaccination in infectious disease management and eradication. (6)

This evidence refutes the IAS's claim. As one research study, "Impact of anti-vaccine movements on pertussis control: the untold story", illustrated, there is strong evidence of a causal relation between pertussis epidemics and the activity of anti-vaccination movements. This research uses data from a range of countries including England, Russia, Japan, Sweden and Italy. (7)

As vaccination coverage increases, both the frequency and severity of epidemics decline. One researcher clearly shows that the incidence of pertussis in five different countries throughout the world, is associated with the level of activity of the anti-vaccination movements and the level of national coverage. "There is no question that these [the anti-vaccination movements] undermine, collectively and individually, the benefits of vaccination." (8)

If there is any validity in the IAS's claim that "98 percent of the total decline in the death rate from measles between 1890 and 1990 occurred before the introduction of the measles vaccination", (9) it is difficult to understand why New Zealand continues to have epidemics and deaths associated with measles. The role immunisation has played in disease control is clearly evident in the New Zealand measles epidemic of 1997.

Mathematical modelling predicted the occurrence of an epidemic in either 1997 or 1998. In 1996 a study of Northland and Auckland showed only an 80.2 percent coverage for first dose of the measles, mumps and rubella (MMR) vaccine, and only 63 to 74 percent coverage in Maori and Pacific Island children. This is insufficient coverage to prevent an epidemic. (10) In order to eradicate measles, a population needs to achieve 95 percent immunisation coverage. A single dose of MMR vaccine protects around 90 percent of children vaccinated, while a second dose will provide immunity from these diseases for 99 percent of children. Unfortunately the second dose of MMR is often missed, leaving both the child and population at risk. Up until the recent modifications to the New Zealand immunisation schedule, the long gap between the two doses of MMR--at 15 months and 11 years--created a pool of susceptible children, which, after several years, allows epidemics to occur.

Measles epidemic

The measles epidemic started earlier than expected, in April 1997, with most cases occurring in the Auckland region. In response, a mass immunisation campaign started in May 1997. The campaign was designed to reduce the number of susceptible children by increasing the seroconversion rates among children who had not responded to their first dose, while providing an opportunity to vaccinate those children who had never received an MMR vaccine. Areas and groups where children were at greater risk were targeted for vaccination, focusing on those who had never been vaccinated and children living in Auckland and north Auckland. The campaign focused on preschoolers, especially those aged under 15 months. (10) This resulted in 57 percent of children aged six to 11 months being vaccinated, while only 56 percent of six to 11-year-olds achieved coverage, although there was considerable variation in coverage both ethnically and geographically. This is far below the desired level for epidemic control but it did provide coverage for the younger age groups, who were more likely to develop complications and therefore be hospitalised. (10)

The epidemic reached its zenith in the first week of July 1997, with 89 cases reported that week. September saw the cases dramatically fall and numbers finally reached a pre-epidemic level by early December, with a total of 1964 cases reported nationwide, 62 percent of which were in the Auckland region. (10)

The efficacy of the immunisation campaign can be evaluated by comparing the actual number of reported cases with the predicted number of cases in the mathematical model. With a predicted total of 21,000 cases, the actual number of cases--1964--fell far short. This reinforces both the value of immunisation for communicable diseases and the effectiveness of mass immunisation campaigns when faced with an imminent epidemic. Despite the lower number of cases than predicted, 175 cases (14 percent), were hospitalised in the Auckland region. (10)

Before 1997, the last measles epidemics had been in 1991 when seven deaths occurred. On the best data available, the next measles epidemic is predicted to arrive anytime from now on, unless we can achieve 95 percent coverage. Closing the gap by bringing the 11-year-old dose down to four years of age and markedly improving our national coverage will stop epidemics occurring.

The impact of vaccination on the health of the world population cannot be over emphasised, despite improved living standards and modern drugs. The claims by anti-immunisation societies that the diseases are on the decline and, therefore, vaccination is unnecessary, holds implications and obligations for health professionals. As health practitioners, it is important to make people aware of events in both New Zealand and other countries where immunisation rates have fallen, and where vaccine preventable diseases have re-emerged. As professionals and vaccinators, we must attempt to refute the notion that diseases will disappear of their own volition. At the same time, we must also increase the public's faith in vaccination and health professionals' advice. We must strive to provide knowledge and support for people who have no medical or health background in a way that not only increases their knowledge but also their understanding and faith in vaccines. This will help achieve the required levels of coverage for population protection from communicable diseases.

This article was reviewed by Kai Tiaki Nursing New Zealand's editorial committee in October this year. The committee also drew on the expertise of the Immunisation Advisory Centre's national immunisation communications adviser Natalie Desmond.

References

(1) Buchan, G. (2003) I think, therefore I vaccinate. New Zealand Immunisation Conference, September, Christchurch.

(2) Leask, J-A. & Chapman, S. (1998) An attempt to swindle nature: press anti-immunisation reportage 1993-1997. Australian and New Zealand Journal of Public Health; 22: 1.

(3) Immunisation Advisory Centre: http://www.imac.auckland.ac.nz.

(4) Immunisation Advisory Centre. A critique by the Immunisation Advisory Centre of the Immunisation Awareness Society pamphlet, What's all this fuss about? http://www.ias.org.nz/ias_brochure.pdf.

(5) McKinnlay, J.B. & McKinnlay, S.M. The questionable contribution of medical measures to the decline of mortality in the United States in the twentieth century. Milbank Memorial Fund Quarterly, Summer, 405-428. cited 'What's all this fuss about', Immunisation Awareness Society pamphlet, http://www.ias.org.nz/ias_brochure.pdf.

(6) http://www.imac.auckland.ac.nz/htm/.

(7) Gangarosa, A M. et al, (1998) Impact of anti-vaccine movements on pertussis control: the untold story, The Lancet, January 31, 351, 356-61.

(8) Hoyt, W.J. Jr. (2004) Anti-vaccination fever--the shot hurt around the world, Skeptical Inquirer; 28: 1.

(9) http://www.ias.org.nz.

(10) Jones. N., et al. (1998) Epidemiology and control of the 1997 measles epidemic in Auckland. 10th Colloquium Proceedings of the Spatial Information Research Centre.

EXPERTS CONFIRM SAFETY OF MeNZB[TM]

A panel of international experts, the Independent Safety Monitoring Board (ISMB) has no concerns about the safety of the meningococcal B vaccine, MeNZB[TM]. This month the board considered safety data for the first two months of the country's largest immunisation programme--from July 19 to September 19, during which more than 140,000 doses of the vaccine were administered. The board advised meningococcal vaccine strategy director Jane O'Hallahan that it had no particular safety concerns.

The Centre for Adverse Reactions Monitoring has also asked health professionals to report adverse events following vaccination with MeNZB[TM]. By late September it had received 88 reports but none were the threatening or unexpected, O'Hallahan said.

Over the next two years, the programme aims to immunise more than one million people aged between six months and 19 years.

Carolyn Hyde RN, MA, does relief practice nursing in the Auckland region, is a certified vaccinator and is studying for a post graduate diploma in hearth informatics.